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Gene defect in toxin clearance associated with pre-eclampsia in pregnancy

A polymorphism in the gene for microsomal epoxide hydrolase is associated with pre-eclampsia 2001; 38: 234-7

A defect in the gene responsible for producing an enzyme that clears toxic compounds in the body may increase the risk of pre-eclampsia, shows research in the Journal of Medical Genetics.

Pre-eclampsia occurs only during pregnancy, and usually during the later part. Characterised by high blood pressure, swelling, and protein in the urine, it affects both mother and baby. Pre-eclampsia progresses rapidly if left untreated, and can be fatal. Around one in 20 pregnancies is affected.

Researchers looked for genetic defects in the blood samples of 183 women who were not pregnant, but who had a history of pre-eclampsia, and 151 healthy women. The women were roughly the same age.

The researchers focused on the gene responsible for the production of the enzyme epoxide hydrolase, which has a vital role in breaking down toxic compounds taken in ,or produced by, the body. They looked for defects in two sections of the gene¾exon 3 and exon 4. An exon 3 defect exaggerates the levels of epoxide hydrolase in the body.

Women with a history of pre-eclampsia were almost twice as likely to carry the exon 3 defect as healthy women, with three out of 10 of them affected. Only one in six of the healthy women had this defect. There were no differences in the prevalence of exon 4 between the two groups.

Ninety six of the women with a history of pre-eclampsia had developed a syndrome known as HELLP¾abnormally high liver enzymes and blood cell irregularities¾which is frequently associated with pre-eclampsia. But there was no difference in the genetic profiles of those who had and did not have the syndrome.

In most circumstances, say the authors, epoxide hydrolase prevents reactive substances in the body from damaging cells, but studies have shown that the enzyme can also activate other harmful compounds. And they conclude that an imbalance between toxic compounds and substances that neutralise and clear these toxins may be important in the development of pre-eclampsia.

Contact:

Dr Eric Steegers, Department of Obstetrics and Gynaecology, University Hospital Nijmegen, The Netherlands.

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